(a) Field of the Invention
The present invention relates to a thin film transistor array panel for a liquid crystal display having a wide viewing angle and a method for manufacturing the same.
(b) Description of the Related Art
Liquid crystal displays (LCDs) typically include two substrates and a liquid crystal layer interposed between the substrates. The transmittance of light is controlled by the intensity of an electric field applied to the liquid crystal layer.
In a vertically aligned (VA) mode LCD, liquid crystal molecules take on a homeotropic orientation in which long axes of the molecules are perpendicular to the substrate. With this configuration, light is cut off almost completely in an xe2x80x9coffxe2x80x9d state where an electric field above a certain value is not applied to the liquid crystal layer. In a normally black mode, since brightness in the off state is extremely low, a significantly higher contrast ratio can be obtained compared to a conventional twisted nematic LCD. However, a tilt direction of the liquid crystal molecules in an xe2x80x9conxe2x80x9d state, in which an electric field above a certain value is applied between the electrodes, is irregular such that a direction of the long axes of some liquid crystal molecules is identical with a polarizing direction of either an upper or lower polarizer film. In these areas, the liquid crystal molecules are unable to rotate the polarizing direction of light, thereby resulting in the blocking of light by the polarizer films. These parts of the LCD appear black, degrading picture quality.
In the meantime, in order to prevent the delay or distortion of signals applied to wires, it is desirable that materials having low resistivity such as aluminum or aluminum alloy are used. However, the aluminum or aluminum alloy is prone to oxidation or corrosion when contacting an ITO (indium tin oxide) layer used for a pixel electrode or a pad.
Furthermore, since the aluminum or aluminum alloy is easily damaged by ITO etchant, the wires made of the aluminum or aluminum alloy may be cut off. Etching the ITO layer by a dry etch method to etch ITO may eliminate this problem, but it costs more.
It is an object of the present invention to provide a thin film transistor array panel for a liquid crystal display having a wide viewing angle and a method for manufacturing the same that can prevent damaging aluminum or aluminum alloy wires by eliminating the contact between the ITO layer and the aluminum or aluminum alloy wire.
These and other objects are provided, according to the present invention, by forming a pixel electrode of ITO before forming a data. The data wire is formed of a double-layered structure, wherein the lower layer has good contacting properties with ITO and an upper layer has a low resistivity.
In another manufacturing method according to the present invention, a gate wire is formed and a pixel electrode of transparent conductive material is formed in a pixel region. Then, a data wire is formed and finally a passivation layer pattern that covers the data wire and having an opening exposing the pixel electrode is formed.
In this manufacturing method, the gate insulating layer pattern, the semiconductor pattern and the ohmic contact layer pattern are formed by a photolithography etch process using one mask, and has a shape similar to the gate wire.
The pixel electrode may be shaped having a plurality of squares with rounded comers connected to each other, or having an open pattern formed of a square shape, a saw-tooth shape or a cross shape. A storage electrode of the storage wire may have various shapes.